This study systematically tests an integrated nursing intervention program for use with irritable infants and their families, the REST Regimen for Infant Irritability. The program has two major components: one focuses on the infant - Regulation, Entrainment, Structure and Touch; and the other focused on the parent - Reassurance, Empathy, Support, and Time-Out. The program is delivered in the home by a team of advanced practice nurses and incorporates the use of infant behavioral assessment, pattern recognition, videotapes, parent support, and other educational materials. Families with irritable infants between 2 to 4 weeks of age will be recruited and screened for health problems and for the level of irritability using the Neonatal Perception Inventory and the Fussiness Rating Scale. Families that meet study criteria (N=160) will be randomly assigned to receive either the REST Regimen or routine well-child care for a 4-week period. A separate, trained evaluation team will take measurements at baseline and at pre-specified intervals during the next 4 weeks following the intervention to assess the following: (a) parental stress using the Parenting Stress Index, (b) parent-infant interaction using the Nursing Child Assessment Feeding Scale, (c) infant state organization using the LifeWatch II Monitor, and (d) infant irritability using the Fussiness Rating Scale. This design and multivariate analysis of variance will test the four hypotheses that REST Regimen results in reduced parental stress, enhanced dyadic synchrony, increased state stability, and diminished unexplained crying. The long-term goals for this research are to supply practicing nurses with a useful and effective framework for intervening with irritable infants and to improve the quality of life for families struggling to cope with these challenging infants.